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05-15-2008, 11:44 PM
I’ve just completed my Kerdi Shower. All the advice from here was fantastic. However I have one issue which I think may be related to my plumbing design rather than the Kerdi Drain. When I run the shower the 2” PVC drain is fast but very loud. It is not a gasping for air type of noise but really just sounds like water running down a drain in stereo. I have a two shower head set up and it is about the same level of noise regardless of flow rate.

The drain exits the floor right on top of a cinder block wall in my basement. I had to relocate the trap a bit to clear the wall. I suspect that may be my problem. The set up is as follows:

Almost on bottom of kerdi drain is a 90 followed by 10inches of horizontally pitched PVC another 90 due south followed by 14” of Vertical PVC which ends in the trap. The trap then ends in a 4” vent pipe about 12 inches away and I added a 1 ½ inch vent tee in between the end of the trap and the vent pipe just after the trap for good measure. All tolled the Trap is about 24 inches below the shower floor and about 12 inches east of it.

Any thoughts on why this set up is so loud. Sound Insulation, fine mesh hair strainer a possiblity to dampen? Is there one available for kerdi drains?

If I get the chisel out and remove some of the wall in the basement I could probably get the trap closer to the drain but it would still be 8-12 inches east but would only be about 8-12 inches south from the shower floor.

Thanks in advance for any thoughts you may have.

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05-16-2008, 04:48 AM
I don't know if this is the problem, but my old copy of the Standard Plumbing Code prohibits a vent within 2 pipe diameters of the weir of a trap. The weir is where the trap goes from vertical to horizontal on the downstream side of the trap. Also, a clean out is required since your shower is not directly above the trap.

05-16-2008, 08:15 AM
My Vote Is Defective Water!

05-16-2008, 08:28 AM
First, I believe your trap is not to code on 2 levels:

1. The trap has to be within a certain distance to the drain.
2. There's a max allowable drop of the trap.

Besides not being to code, the way you have the trap now increases the risk of the trap siphoning - especially the vertical drop. Where's your vent break in all this?

I believe the sound yr hearing is the water dropping down to the trap and then being amplified by all that pipe up to the drain. If you're not noticing the trap siphoning (i.e., no sewer gasses when shower's off) then I'd just live with the sound.

If you ARE noticing gasses, then after yr done showering each time, leave one shower head on at a slow trickle for 1min. This will help refill the trap without causing such a rush that it siphons again.

And if you ever have to sell, do what you can to mask yr trap design to any inspector ;)

05-16-2008, 09:07 AM
1. The trap has to be within a certain distance to the drain.
2. There's a max allowable drop of the trap.Unless things have changed a lot, I think he's within tolerance. My old book says 24 inches max drop, and horizontal length is based on dry venting rules, which I think he passes.

05-16-2008, 10:46 AM
Ideally, the trap is directly underneath the drain with a fairly short drop. Keep in mind what the trap is designed to do - keep sewer gasses and outgassing from the crud on the pipe walls from coming back into the house. By having a long trap arm, any hair, body oil, soap scum, conditioner leftovers that stick to the walls of the pipe can fester and have a direct feed into the house. Not a good setup at all. WHen there is only a short drop to the trap, all of that is blocked off and the speed of the flow tends to keep that short drop clean. A picture would help clarify the description.

05-16-2008, 08:38 PM
thanks for the quick replies. With a wife with long hair i did put in a clean out which partially lead to the design and easy access. Also opened the plug on the bottom of the trap and plenty of water came out so no sipohning. I think prashster hit it on the money about the water echoing from its fall down the vertical pipe before the trap. It is just way to loud to leave.

Reviewing the situation i could place the trap within about 6-8 inches on the pitched horizontal slope right after the drain.(rember i have a immediate 90 on the end of my kerdi drain). That would place the trap 6-8 inches from the drain and about 6-8 inches height from the shower floor. That should solve my water fall effect, However now i'm not on plane with where the trap needs to enter the stack. (way high)

One question how far does the weir side of the trap need to run horizontally (pitched of course) before i can drop it the needed 14 or so inches to the stack? I don't want to make it an S trap inadvertantly. I'm thinking it would be close to a foot, foot and a half or horizontal run, before i have to drop it the 14 or so inches to connect it to the stack. The other option would be to gradually drop the plane until it is on the right level.

Thanks again!

05-16-2008, 09:10 PM
After the trap weir you need a vent break. After the vent break, you can drop down. The break stops it from being an 's' trap.

05-17-2008, 07:43 AM
And again, the vent needs to be at least 2 pipe diameters downstream of the trap weir.

05-18-2008, 01:41 AM
Try the mesh hair strainer.

The kerdi drains use to have one and they did help with drain noise.
Too bad Schluter decided to quit using them. :(

crow wing
05-18-2008, 02:09 AM
Trap needs to be a nice U shape not a flat l____l .and should be directly under drain.
I think its the two 90 deg fittings causing cavitaction.
Never had a problem with a long drop or a vent being close to trap.

John Bridge
05-18-2008, 09:25 AM
1. I don't think you have a problem. Try insulating the entire drain line or whatever portion you can get to.

2. I would never add an additional vent to anything. ;)

3. The Kerdi-drain hair strainer was discontinued because it clogged easily and frequently with hair. It was becoming a pain. Too many complaints. :)